Battery drain

[cheeseandbeans]

How old is the battery? 5 years or more (or approaching 5 years) then I'd replace it. I had a similar issue and was convinced I had a drain somewhere and thought the battery looked newish (clearly because it sits in the boot as not exposed to the elements) and then I spoke to the previous owner who had the car for 8 years and had never replaced it! New battery fitted and never had any more problems..

Only bought this battery 12 months ago for another Z I had. Transferred it into this car.

 

[cheeseandbeans]

I had a duff alternator discovered it was at fault after using the car at night with headlights on, next day battery flat.
On checking alternator it was only putting out 12v not the 14v it should have been with engine running. Easy to check with a voltmeter on the battery terminals with engine running. Now have a small voltmeter that plugs in the cig lighter socket to keep an eye on charging state. Replacing alternator put it right.

Hi, can you explain further how I go about checking the alternator? I've bought a multimeter so I'm good to go

 

[cheeseandbeans]

One last thing. If the car is off what should I see from the multimeter on the battery?

 

[littlefeller]

ideally no lower than 12.6v, alternator output should be high 13v to low 14's

 

[Tracy Dee]

With every conceivable electrical item switched on my car runs at 13.8 v

 

[littlefeller]

then your alternator is running fine, your drain is somewhere else, did you ever get to the bottom of it? (13.8 is at the lower level but ok)

 

[Tracy Dee]

Yes its at lower level but that's with every single electrical item on Tony said it's exceptable charging not 100 % but serviceable won't drain battery running and how often is every item on.
I now use a battery isolator when not in use with the occasional trickle charge of a couple of hours if not used for a week or two.

 

[cheeseandbeans]

Ok as it stands. Car turned off I'm getting 12.31v at the battery car turned on I'm getting 13.92v at the battery. Will test again in the morning.

 

[littlefeller]

12.3 is a little low, 13.9 is ok, again its on the lower limit, your battery will have 6 cells each cell should be 2.1v giving a total of 12.6. with the battery running lower than 12.6 i would hazard a guess that the 13.9 may not be enough to maintain the battery at 12.3. give it a good run and try again, the other thing to do is measure how much loasd-draw is on the battery with the engine off.

 

[littlefeller]

oh yeh just a heads up- do not test drain directly to battery terminals or you may blow your meter. (this isnt very clear, ok if your using your meter set to amps then dont put it across the battery, you would need to remove one of the battery leads and connect the meter in line)

 

[cheeseandbeans]

oh yeh just a heads up- do not test drain directly to battery terminals or you may blow your meter. (this isnt very clear, ok if your using your meter set to amps then dont put it across the battery, you would need to remove one of the battery leads and connect the meter in line)

Ok thanks, where do you suggest i test instead then? Also how do I test the load/draw? Apologies for the questions, never really used a multimeter before so I'm learning on the job

 

[littlefeller]

thats ok, you need to set your meter to Amps, there should be a low and high setting, always go for high setting, and when finished switch the meter back to volts (just to be safe for the meter).
you need to disconnect the positive lead from the battery, your meter now needs to be the bridge back to the battery.

hang on a minute, i will find a link

got one http://www.wikihow.com/Find-a-Parasitic-Battery-Drain

 

[Dobiwallah]

Hi, if you just measure over each fuse one by one with your amp meter, (remove the fuse first of course) you can see which one is having the most drain. Theoretically, if your battery is about 45Ah, and in good health, the drain current should be 45Ah divided by 48 hours(you said by day 3 its empty) = 0.93A total.

I had the same problem, it turned out to be my android phone with Torque and Bluetooth left on in the cradle in the weekend.


Something like this, (my red pin is not so good placed, I had to take the photo in the dark)

 

[cheeseandbeans]

Well I think I've found it with all your advice and it was staring me in the face all the time. The CD changer in the boot looks to be the culprit! When I was checking for draw on amps it was showing 0.21, unplugged the CD changer and it's 0.01 now! Absolutely brilliant. Thanks again for all your valuable assistance. Don't need to keep charging the battery now

 

[Dobiwallah]

Glad it all worked out

 

[colb]

So why is it drawing current when the car is switched off? Could it be controlled through a relay that is stuck on?

 

[markvrs]

CD multiplayer has a permanent live connection to allow disc to be ejected without key in ignition.

It is a useful permanent live in the boot if you wish to bypass the brake pedal to lower the roof

 

[littlefeller]

great job, now get yourself down to @Tracy Dee and fix hers

 

[colb]

If its a live feed to the changer that is causing the battery drain, whats the fix, is it something to do with a faulty changer or is his battery on its way out and can't cope with the draw?

 

[cheeseandbeans]

What I will say is it's an aftermarket stereo and cd changer. Not fitted by myself. Not too fussed about it really as the head unit is a mini disk player! Will swap it out at some point.